On the morning of Sept. 23 in 1780, three ordinary militiamen stopped a stranger on a road, searched him, found treason hidden in his boot, turned down a small fortune to let him walk, and in doing so saved West Point and possibly the whole Revolution. Their names were John Paulding, Isaac Van Wart, and David Williams, and almost no one remembers them. They were young New York farmers, part of the informal patrols that watched the dangerous no-man's-land north of British-occupied New York City, a lawless strip crawling with raiders and spies from both sides. On this morning, near Tarrytown, they stopped a well-dressed rider who called himself John Anderson.